One implementation of a sensing method includes: correlating a receive signal with a first channel waveform template to obtain a first channel correlation signal in which first channel echoes would be represented as peaks; correlating the receive signal with a second channel waveform template to obtain a second channel correlation signal in which second channel echoes would be represented as peaks; and varying the first channel waveform template and the second channel waveform template based on time elapsed from a measurement start time. A sensor array implementation includes: multiple acoustic transducers that operate concurrently to send acoustic bursts in different frequency channels, each of the multiple acoustic transducers configured to use the foregoing method.